Cordless rechargeable battery powered drive assemblies for driving orthopedic surgical instruments have been known for many years. Such drive assemblies for example, are presently available from Stryker, Kalamazoo, Mich. as their Series 90 instruments and from Dyonics, Andover, Mass. as their Cordless 200 Reamer or their Cordless 450 Orthopedic Drill. These assemblies utilize batteries having cells containing nickel and cadmium electrodes which store and provide power to an electric direct current activated drive motor in the assembly.
These drive assemblies, however, have not been as convenient to use as might be desired because the combination of the battery chemistry and the direct current motors used in these assemblies does not provide sufficient power to complete many of the procedures undertaken in orthopedic surgery. Thus, batteries must be changed during those procedures which is inconvenient and time consuming.
Also, the rechargeable batteries for these drive assemblies have not been as durable as might be desired due to repeated high temperature (e.g. 270.degree. F.) sterilization in autoclaves required so that the batteries may be used during surgery. Typically the batteries must be replaced after a relatively small number of uses (e.g., 20 to 30) which significantly affects the cost of using the drive assemblies.